JPH0238011A - Mold for compression molding - Google Patents

Abstract

PURPOSE:To absorb efficiently the weighing error of a molding material, and obtain an accurate molding article by providing a through hole absorbing an excessive molding material in piercing a mold forming a cavity, and a press-pin to be slid into the through hole and capable of being operated in freely advancing and retreating from the outside of the mold. CONSTITUTION:Upon molding, although a molding material is filled into the through hole opened communicatingly to a cavity, a core 31 and a cavity surface 12 are combined, after that, a complete molding is carried out in supplementing a molding material to a non-filled part by urging a supporting plate 33 to be pressed downwards by a rod 34 and a press-pin 32 to be thrust therein. In this manner, the press-pin 32 may control the thrusting degree in accordance with the dispersion of the supplied molding material, thereby not producing any burr in acting as a way of escape for molding material in the case wherein the molding material is excessive, and not existing any non-filled part in supplementing by the molding material to be filled into the through hole in the case wherein the molding material is insufficient. Thus, the quality dispersion of product can be avoided.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a compression mold.

(Prior art) Compression molding involves supplying powdered molding material into a heated mold, melting the molding material, and applying pressure to mold the material.As a simple molding method, it is not often used in resin molding. There is.

Conventional compression molding molds include flush molds, positive molds, etc., depending on the structure of the molding mold.

The flash mold is configured so that a slightly larger amount of molding material than necessary for molding is supplied and the excess molding material flows out of the cavity during molding. This type of mold has the advantage that there is no need to precisely weigh the molding material and that the mold is easy to manufacture. The disadvantage is that it is difficult to apply pressure and the density of the molded product is low.

In addition, the positive mold has a piston structure in which the male and female molds fit together to prevent the molding material from flowing out of the cavity. Although the density increases, the molding material must be accurately weighed and supplied in order to obtain a good product.

(Problem to be solved by the invention) As mentioned above, each conventional compression molding mold has its own characteristics, but the basic problem is that the material used as the molding material is powder or granules with irregular grain sizes. Because of its shape, there is a problem in that accurate weighing is inherently difficult.

That is, in the case of a molding material containing a mixture of powder and granules, there is usually an error of about 3% in the amount of material supplied.

This variation in supply amount causes product variation and non-filling. In the flash mold, problems such as weighing errors and unfilled molding materials are eliminated by using a slightly larger amount of molding material, but in the positive mold, variations in the amount of molding material supplied directly affect the shape of the product.

In addition, another problem is when molding without creating a gap,
There is a problem in that molding becomes extremely difficult depending on the shape of the product. In other words, in this case, a positive mold will be used, but if you want to use this mold to mold a product with a notch (unevenness) on the outer surface of the flange as shown in Figure 3, the outer surface should be made into an uneven surface. In order to mold the product, the sliding surfaces of the male and female molds must be formed into an uneven surface that matches the external shape of the product. However, forming the sliding surface of the mold into a complex uneven surface is difficult to manufacture, and is almost impossible in terms of cost.

Therefore, the present invention has been made to solve the above problems, and its first object is to effectively absorb weighing errors of molding materials and obtain molded products with high precision. To provide a compression molding mold that can easily mold even a product having a complicated external shape without forming a part, and can also easily manufacture the mold.

(Means for Solving the Problems) The present invention has the following configuration to achieve the above object.

That is, a through-hole is opened on the inner surface of the mold forming a cavity that regulates the outer shape of the molded product to be obtained, a through-hole is provided through the mold forming the cavity to absorb excess molding material, and a through-hole is provided through the mold forming the cavity. The mold is characterized by being provided with a push pin that is inserted into the mold and can be operated to move forward and backward from outside the mold, and a control means for controlling the molding pressure by pressing the push pin is provided in conjunction with the push pin. It is characterized by a lower mold having a recessed cavity surface that regulates the outer shape of the molded product to be obtained, and a core having a cavity surface formed at the tip that regulates the inner shape and outer peripheral end surface of the molded product to be obtained. an upper mold that forms a molding cavity when the mold is closed relative to the lower mold, and a core insertion hole into which the core can be inserted, and a hole between the lower mold and the upper mold. In a compression molding mold having an intermediate plate movably interposed in the mold opening/closing direction, the upper mold is penetrated and opened on the cavity surface of the core to remove excess molding material. It is characterized by providing a through hole for absorption, and providing a push pin that is inserted into the through hole and can be freely moved forward and backward from the outside of the mold,
Further, the peripheral surface of the core insertion hole of the intermediate plate facing the lower mold is formed as a cavity surface that regulates all or part of the outer peripheral end surface of the molded product to be obtained, and When closing, the lower mold and intermediate plate are matched and then the upper mold is matched to close the mold. When opening the mold, the lower mold is first separated from the intermediate plate, and then the intermediate plate is separated from the upper mold. It is characterized by having a mold closing/opening mechanism.

(Function) When molding is performed by matching the molds, the amount of molding material filled into the through hole is adjusted by adjusting the amount of thrust of the push pin inserted into the through hole. By adjusting the amount of thrust of the push pin, variations in the amount of supplied molding material due to weighing errors can be absorbed.

In addition, when using a mold equipped with an upper mold, a lower mold, and an intermediate plate, when the mold is closed, the lower mold and the intermediate plate are aligned to supply the molding material into the cavity, and then,
−Mold by matching with the mold. During this molding, the amount of thrust of the push pins is adjusted to perform the molding. When opening the mold, the lower mold is first separated from the intermediate plate, and then the intermediate plate is separated from the upper mold. When the intermediate plate is separated from the upper mold, the molded product remaining in the core is pushed out by the intermediate plate and released from the core.

(Embodiments) Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Figures 1 and 2 are explanatory diagrams showing one embodiment of a compression molding mold according to the present invention, with Figure 1 showing the state of the mold when the mold is opened, and Figure 2 showing the state of the mold when the mold is closed. .

In the figure, 10 is a lower mold, an intermediate plate 20 is located on the - side of the lower mold, and an upper mold 30 is located further above the intermediate plate 20.

The lower mold 10 is fixed on the base 1 [, and the base 11 is linked to a drive unit that vertically moves the base up and down in response to mold opening and mold closing. ] 2 is a cavity surface recessed in the upper surface of the lower mold 10.

A flash ridge (mold fitting) 13 formed in the shape of a narrow protrusion is provided at the upper peripheral portion of the cavity surface 12. When the lower mold 1.0 is molded to the intermediate plate 1 20, this flash ridge 13 comes into contact with the lower surface of the intermediate plate 20 and acts as a stopper. 14 is a guide pin fixed to the base 11-A.

The intermediate plate 20 is supported horizontally by having one end fixed to a screw I/N rod 22 that is connected to a hydraulic cylinder 21 and moves up and down in the vertical direction. Intermediate play when opening the mold] ~20
is located approximately midway between the lower mold 10 and the upper mold 30.

Reference numerals 2 and 3 denote a core insertion hole into which the core of the upper mold is inserted, and is provided penetratingly at a position corresponding to the cavity surface 12 of the intermediate plate 20. 14a is a guide pin bush.

The upper mold 30 is fixedly supported by the frame, and the upper mold 30 is provided with a protruding core 31 that fits into the core insertion hole 23 and fits into the cavity surface 12. This core 31 forms a molding cavity with the cavity surface 12 when the mold is closed, and a cavity surface is provided at the tip of the core 31 to regulate the inner shape and outer peripheral end surface of the molded product.

Note that 32 is a push pin formed in the shape of a long thin rod, and is slid into a through hole provided vertically through the upper mold 30 from the lower surface of the core 31. In this embodiment, two through holes are provided so as to communicate with the cavity formed by the cavity surface 12 and the cavity surface of the core 31, but these through holes are provided at locations that will not cause any problems in the structure of the product. In addition, if there is no suitable place to open a through hole due to the structure of the product, or if unnecessary parts are to be removed in a post-process, the opening of the through hole should be limited to places where it will not cause any problems. There's no need.

The upper end of the push pin 32 is fixed to the lower surface of a support plate 33 which is housed in the mold 30 so as to be movable in the vertical direction. 3
A rod 34 is disposed to push 3 downward. 35 is a guide fixed to the lower surface of the support plate 33, and the lower part of the guide 35 is slid into the guide hole 36. The support plate 33 is a guide 35
It is supported and always biased vertically upward by a coil spring inserted into the body.

37 is a guide pin, and 37r1.37b are guide pin bushes provided on the intermediate plate 20 and the lower mold 10, respectively.

Next, the operation of the compression molding mold of the above embodiment and the compression molding method using this mold will be explained.

First, from the mold open state shown in FIG.
Type match with 0. Thereby, the cavity surface 12 and the core insertion hole 23 are connected.

A predetermined amount of molding material is supplied into the cavity surface 12 while the cavity surface 12 and the core insertion hole 23 are connected. The supplied molding material will not leak out because the lower mold 10 and the intermediate plate 20 are perfectly matched, and the lower mold 10 is preheated to a temperature that melts the molding material.

Next, the intermediate plate 20 containing the molding material and the lower mold 10 are raised toward the upper mold 30 while being connected, and the molds are matched with the upper mold 30. At this time, the core 31 gradually enters the core insertion hole 23, forms a molding cavity with the cavity surface 12 as shown in FIG. 2, and molds the molten molding material into a predetermined shape. . At the time of molding, pressure is applied from the intermediate plate 20 to the lower mold 10 so that no cracks come out from the mold mating surface between the intermediate plate 20 and the lower mold 10.

During this molding, the molding material is also filled into the through hole that opens and communicates with the cavity, but after the core 31 and the cavity surface 12 are assembled, the support plate 33 is pushed downward by the rod 34. and push the push pin 32 in. By inserting the push pin 32, the unfilled portion is replenished with molding material and complete molding is performed.
It explains the state before and after entering.

After the molding is completed, the lower mold 10 is first separated from the intermediate plate 20 and lowered. Since the molded product shrinks after molding, the molded product remains attached to the core 31.

Next, the intermediate plate 20 is separated from the upper mold 30 and lowered. Since the outer peripheral end surface of the molded product is in contact with the periphery of the lower surface of the core insertion hole 23 of the intermediate plate 20, the molded product is separated from the core 31 by being projected by the intermediate plate 20.

With the above steps, the steps from supplying the molding material to molding the molding material and releasing the molded product are completed.

1- Due to the above-mentioned action, the operation using the push pin 32 causes variations in the amount of molding material supplied due to weighing errors,
This eliminates the problem of product variations. In other words, when molding the molding material, the push pins 32 move toward the cavity surface 1 if the molding material is slightly less.
2, and if there is a little more molding material, the push pin will only be pushed in a little, and in this case, the preformed part will remain in the molded product. If the preformed part is located in a part that will not cause any structural defects even if it is formed on the product, it may be left as is, or if it needs to be removed for structural reasons, it can be removed in a subsequent process to produce a complete product. Since the through-holes are provided in advance at predetermined positions, after molding, there will be removed portions at predetermined positions, and the removal work in subsequent steps will be easy.

In this way, the push pin 32 adjusts the protrusion amount of the push pin 32 according to the variation in the supplied molding material, so that if there is excess molding material, it acts as an escape for the molding material and prevents the breakage. If the amount of molding material is low, it can be supplemented with the molding material filled into the through hole, thereby preventing unfilled areas from appearing. That is, by absorbing variations in the amount of molding material supplied by the amount filled into the through-hole, it is possible to eliminate product variations.

Furthermore, the push pins 32 can be used to finely adjust the molding pressure when molding the core 31 and the cavity surface 12, thereby making it possible to perform molding more reliably. In this case, in order to control the suppressing force of the push pin 32, a separate control mechanism can be provided for controlling the push pin, and the control mechanism may include, for example, a push pin connected to a cylinder, or a servo motor connected to the push pin. Various control means can be employed.

Further, the push pin 32 can also be used as an ejector for releasing the molded product.

The product molded in Example 1-1 is a box-shaped product with an open top as shown in FIG.

This product has a flange 40 with unevenness on the upper outer peripheral surface.
was established. Products with complex irregularities on the outer surface cannot be easily molded using conventional compression molds. However, in the mold of Example -1-, the outer surface forming part below the flange 40 is composed of the cavity surface 12 part of the lower mold 10, and the core insertion hole 23 is formed at the two points shown in FIG. 3(a). By forming a simple rectangular area shown by the chain line, it can be formed into a cylinder. The core 31 is manufactured into a predetermined shape depending on the internal structure and wall thickness of the product.

With the mold of the full bending example, the complex shape of the outer surface of the product can be processed with only the shape of the lower mold 10, and the core 31
The shape of the mold is also the same as that of conventional molds.

Therefore, when manufacturing a mold, there is no need to create a mating hole according to the complex external shape, and the difficulties associated with mold manufacturing can be solved, and the cost is also 1 to 1. - Can be manufactured in minutes. In the figure, reference numeral 41 indicates the preformed portion remaining after being filled in the through hole.

In addition, -1- In the example described above, a mold equipped with an intermediate plate etc. was explained so that even a product with a complicated shape can be easily molded. Of course, it is also possible to provide the pin structure in a commonly used compression mold as shown in FIG. In the figure, 50 is a single mold, 50a is a cavity part, 51 is a -1-mold, and 52 is a push pin (t' inserted into a through hole) provided in the -mold.Push pin 5
The operation of No. 2 is similar to that of the above-mentioned embodiment, and by adjusting the amount of thrust of the push pin, it is possible to absorb the weighing error of the molding material and mold the molding material with high accuracy. In addition, the push pin 52
It can also be used for ejecting molded products.

In each of the two consecutive embodiments, an example was described in which a push pin was provided on the -1- mold side, but the placement position of the push pin is not limited to the - mold.

The same arrangement can be made in the lower mold and the like. Since the push pins are used to correct weighing errors and adjust molding pressure, they can be provided at any appropriate location in the mold as long as it communicates with the cavity. If it is provided in a location that will be exposed to the outside as a product, the unnecessary Mr portion can be removed through post-processing as described above, and the product can be manufactured.

In this case, since unnecessary portions are generated at certain locations, mechanical processing can be performed in post-processing, which is advantageous.

1. Although various explanations have been given of the present invention using preferred embodiments, the present invention is not limited to these embodiments, and the shape of the cavity and core can be changed as appropriate depending on the shape and size of the molded product. It can be formed into any shape, and the number and size of push pins and through holes can be set as appropriate.

(Effects of the Invention) According to the compression molding mold of the present invention, configured as described above, the following remarkable effects are achieved. In other words, ■ By providing a through hole in the mold and sliding a push pin into the through hole, the amount of thrust of the push pin can be adjusted.
Variations in the amount of molding material supplied due to weighing errors can be absorbed by the plunge amount of the push pin.

It is possible to suppress variations in wall thickness, etc. of molded products, and provide products with high precision.

(2) In addition, by appropriately adjusting the amount of push-in of the push pin, it is possible to prevent the appearance of cracks in the molded product and to prevent unfilled areas from occurring.

■ ] When using a mold with a double-mold lower mold and an intermediate plate, even products with complex external shapes can be easily molded, and mold manufacturing becomes easier. Therefore, even products with shapes that were previously impossible can be easily commercialized.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams showing the states of the compression molding mold according to the present invention when the mold is opened and when the mold is closed, and FIG. 3 (a
), (b) are a plan view, a side view, and a fourth example of a molded product.
The figure is an explanatory diagram showing another embodiment of the compression molding mold. 10...Lower mold. 20...Intermediate plate, hole, 30...Upper mold, 32...Push pin, 35 40...Flange, 52 12...2;33 Cavity surface,...Core insertion... ·core.・Guide, ・Push pin.

Claims (1)

[Scope of Claims] 1. A through hole is provided through the mold forming the cavity, opening at the inner surface of the mold forming a cavity that regulates the outer shape of the molded product to be obtained, and absorbing excess molding material; A mold for compression molding, characterized in that a push pin is provided which is slid into the through hole and is operated to move forward and backward from the outside of the mold. 2. Claim 1, characterized in that a control means for controlling the molding pressure by pressing the push pin is provided in conjunction with the push pin.
The compression mold described above. 3. The lower mold has a recessed cavity surface that regulates the outer shape of the molded product to be obtained, and a core that has a cavity surface formed at the tip that regulates the inner shape and outer peripheral end surface of the molded product to be obtained. An upper mold that forms a molding cavity when the mold is closed, and a core insertion hole into which the core can be inserted are transparent, and the mold opening/closing direction is formed between the lower mold and the upper mold. In a compression molding mold having an intermediate plate movably interposed in the upper mold, a through hole is provided that penetrates the upper mold, opens on the cavity surface of the core, and absorbs excess molding material. A mold for compression molding, characterized in that a push pin is inserted into the through hole and can be freely moved forward and backward from the outside of the mold. 4. According to claim 3, the peripheral surface of the core insertion hole of the intermediate plate facing the lower mold is formed as a cavity surface that regulates all or part of the outer peripheral end surface of the molded product to be obtained. Mold for compression molding. 5. When closing the mold, align the lower mold and the intermediate plate, then align them with the upper mold and close the mold, and when opening the mold,
5. The compression molding mold according to claim 3, further comprising a mold closing/opening mechanism that first separates the lower mold from the intermediate plate and then separates the intermediate plate from the upper mold.